In many communication systems, the use of numbers, symbols or digits are utilized to identify a destination. Digits representative of a destination can be automatically transmitted, such as to access an Internet web site, dialed automatically from a telephone to reach a called party, or dialed manually by a user of a communication system. In all of these situations, a full complement of digits must be transmitted in order to be properly interconnected to the correct destination.
In those communication systems where a preset or predetermined number of digits must be dialed, the determination of the last digit dialed is determined relatively easily, in that the receiving system simply counts the number of digits dialed. When the prescribed number of digits have been received, the process is carried out to provide an interconnection to the respective destination. When the prescribed number of digits has not been received, it is a common practice to wait a predefined period of time before transmitting a message or tone to the originating party to indicate the receipt of less than all of the prescribed number of digits. A further period of time may lapse before receipt of the full complement of digits from the originating party, otherwise the communication system waiting for the digits simply disconnects the originating party.
The determination of the last digit dialed in other systems can be more complicated, especially when various destinations can be reached by the dialing of different numbers of digits or symbols. For example, the dialing of the single digit “0” is sufficient to reach an operator for assistance. The same is true in many cases when a three-digit number is dialed to reach an operator or to request emergency assistance. In some cases, a seven-digit number is all that is necessary to reach a called party in the public switched telephone network (PSTN). In more recent times, a ten-digit number is required in order to reach a destination in the PSTN. Yet additional digits may be required in placing international calls, credit card calls and calls made from specialized communication systems. From the foregoing, it can be seen that in these situations, and others, it is insufficient to simply count the number of digits before making a determination that the last digit has been dialed.
In general, standard corded telephone sets, as well as cordless and wireless telephone sets, do not make a determination when the last digit has been dialed. Rather, these telephone sets merely transmit the digits as dialed. For instance, in the corded telephone set, each digit is transmitted individually to the central office or PBX switching system as dialed by the user. In cordless telephone sets, the same is true, except that with certain telephone sets when a full complement of digits has been dialed, the user then simply pushes the “talk” button and the digits are automatically transferred to the central office. Similarly, in cellular telephone sets, when the user has input the full complement of digits, the “send” button is pushed, whereupon a data packet is transmitted to the cellular base station. In these latter two situations, it is not the telephone itself that makes a determination wherein the full complement of digits has been dialed, but rather the user of the telephone.
In many communication systems servicing the equipment of users, such as central office and PBX switching systems, there are circuits or programmed operations that are employed to make a determination as to when the last digit was received from the user equipment. The determination of the last digits dialed expedites the call setup and allows the communication system to be more efficiently utilized. The waiting of an inordinately long period of time for a last digit would unnecessarily tie up the resources of the communication system and thereby prevent other potential users from service thereof. The determination of the last digit dialed is often a feature incorporated in central office and PBX systems, communication systems providing SLIC service, as well as wireless local loop telephone systems.
From the foregoing, it can be seen that a need exists for a technique in determining the last digit of a dialed number sequence. Another need exists for an algorithm that can be easily incorporated into telecommunication equipment for determining the last digit dialed. Yet another need exists for a technique that includes a user-selectable dialing speed schedule best adapted to the dialing habits of the user.